Kandel, S. E. | Search bioRxiv

bioRxiv2026

Pseudomonas aeruginosa co-opts host antibiotic metabolism by pyocyanin induction of cytochrome P450 enzymes

The human opportunistic pathogen Pseudomonas aeruginosa produces copious quantities of the secondary metabolite pyocyanin (PYO). PYO has recently been shown to interact with the aryl hydrocarbon receptor (AhR), a transcription factor controlling expression of a number of genes, including the cytochrome P450 CYP1A family involved in fluoroquinolone antibiotic clearance. In this study, we investigated whether Pseudomonas aeruginosa could influence the metabolism of ciprofloxacin through human CYP1A2 induction. Primary human hepatocytes were exposed to 1-100 M PYO, with high concentrations resulting in apparent cytotoxicity. Treatment with 5 {micro}M PYO led to a 6.2-fold change in CYP1A2 mRNA and a 3.6-fold increase in oxociprofloxacin metabolite formation. Our results suggest that sub-toxic concentrations of PYO induce CYP1A2 expression and increase ciprofloxacin metabolism, which could lead to sub-efficacious antibiotic concentrations and further drive resistance. This finding directs us to a novel mechanism by which Pseudomonas aeruginosa may escape antimicrobial therapy by hijacking host xenobiotic metabolism pathways. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/740721v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1b350forg.highwire.dtl.DTLVardef@388eb7org.highwire.dtl.DTLVardef@121bc9aorg.highwire.dtl.DTLVardef@1e53060_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2021

Pseudomonas aeruginosa cytochrome P450 CYP168A1 is a fatty acid hydroxylase that metabolizes arachidonic acid to the vasodilator 19-HETE

Pseudomonas aeruginosa is a gram-negative opportunistic human pathogen that is highly prevalent in individuals with cystic fibrosis (CF). A major problem in treating CF patients infected with P. aeruginosa is the development of antibiotic resistance. Therefore, the identification of novel P. aeruginosa antibiotic drug targets is of the upmost urgency. The genome of P. aeruginosa contains four putative cytochrome P450 enzymes (CYPs) of unknown function that have never before been characterized. Analogous to some of the CYPs from M. tuberculosis, the P. aeruginosa CYPs may be important for growth and colonization of the CF patients lung. In this study, we cloned, expressed, and characterized CYP168A1 from P. aeruginosa and identified it as a sub-terminal fatty acid hydroxylase. Spectral binding data and computational modeling of substrates and inhibitors suggest that CYP168A1 has a large, expansive active site preferring long chain fatty acids and large hydrophobic inhibitors. Furthermore, metabolism experiments confirm that the enzyme is capable of hydroxylating arachidonic acid, an important inflammatory signaling molecule present in abundance in the CF lung, to 19-hydroxyeicosatetraenoic acid (19-HETE; Km = 41.1 {micro}M, Vmax = 222 pmol/min/nmol P450), a potent vasoconstrictor which may play a role in the pathogens ability to colonize the mammalian lung. Metabolism of arachidonic acid is subject to substrate inhibition and is also inhibited by the presence of ketoconazole. This study points to the discovery of a new potential drug target that may be of utility in treating drug resistant P. aeruginosa.

biochemistry↗